Abstract
The role of exocytosis in the human neutrophil respiratory burst was determined using a fusion protein (TAT-SNAP-23) containing the HIV transactivator of transcription (TAT) cell-penetrating sequence and the N-terminal SNARE domain of synaptosome-associated protein-23 (SNAP-23). This agent inhibited stimulated exocytosis of secretory vesicles and gelatinase and specific granules but not azurophil granules. GST pulldown showed that TAT-SNAP-23 bound to the combination of vesicle-associated membrane protein-2 and syntaxin-4 but not to either individually. TAT-SNAP-23 reduced phagocytosis-stimulated hydrogen peroxide production by 60% without affecting phagocytosis or generation of HOCl within phagosomes. TAT-SNAP-23 had no effect on fMLF-stimulated superoxide release but significantly inhibited priming of this response by TNF-α and platelet-activating factor. Pretreatment with TAT-SNAP-23 inhibited the increase in plasma membrane expression of gp91(phox) in TNF-α-primed neutrophils, whereas TNF-α activation of ERK1/2 and p38 MAPK was not affected. The data demonstrate that neutrophil granule exocytosis contributes to phagocytosis-induced respiratory burst activity and plays a critical role in priming of the respiratory burst by increasing expression of membrane components of the NADPH oxidase.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, Non-P.H.S.
MeSH terms
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Apoptosis / genetics
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Apoptosis / immunology
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Cytoplasmic Granules / genetics
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Cytoplasmic Granules / immunology*
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Cytoplasmic Granules / metabolism
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Exocytosis / genetics
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Exocytosis / immunology*
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Gene Products, tat / antagonists & inhibitors
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Gene Products, tat / genetics
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Gene Products, tat / metabolism
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HIV-1 / immunology
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Humans
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Neutrophil Activation / genetics
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Neutrophil Activation / immunology*
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Phagocytosis / genetics
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Phagocytosis / immunology
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Platelet Activating Factor / physiology
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Protein Structure, Tertiary / genetics
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Qb-SNARE Proteins / antagonists & inhibitors
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Qb-SNARE Proteins / genetics
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Qb-SNARE Proteins / metabolism
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Qc-SNARE Proteins / antagonists & inhibitors
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Qc-SNARE Proteins / genetics
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Qc-SNARE Proteins / metabolism
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Recombinant Fusion Proteins / antagonists & inhibitors
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Recombinant Fusion Proteins / metabolism
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Respiratory Burst / genetics
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Respiratory Burst / immunology*
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SNARE Proteins / antagonists & inhibitors
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SNARE Proteins / genetics
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SNARE Proteins / metabolism
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Signal Transduction / genetics
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Signal Transduction / immunology
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Tumor Necrosis Factor-alpha / physiology
Substances
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Gene Products, tat
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Platelet Activating Factor
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Qb-SNARE Proteins
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Qc-SNARE Proteins
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Recombinant Fusion Proteins
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SNAP23 protein, human
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SNARE Proteins
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Tumor Necrosis Factor-alpha